WASHINGTON – Ukraine’s foreign minister said Monday that pro-Russian separatists are continuing to try to manipulate the wreckage of the Malaysian airliner that the United States and others have accused the rebels of shooting down.

In an interview with The Associated Press, Foreign Minister Pavlo Klimkin said new fighting that prevented an international police team from getting to the site earlier Monday was the fault of the separatists who are trying to cover up their involvement. He said a cease-fire in the area of the crash site remains a priority for authorities in Kyiv.

“For us it was an extremely important prerequisite, how to ensure the access to the crash site and how to carry out effective and transparent investigation,” he said. “But of course, it’s about the separatist activities from yesterday but also today. There is no heavy fighting as I understand but they have been trying to wipe out any sort of traces.”

Earlier fighting raged around the debris field, once again preventing an international police team charged with securing the site from getting there. Government troops have stepped up their push to win back territory from the separatists in fighting that the United Nations said Monday has killed more than 1,100 people in four months. The delegation of Australian and Dutch police and forensic experts were stopped in Shakhtarsk, a town around 20 miles (30 kilometres) from the fields where the Boeing 777 was brought down.

Klimkin, who is in Washington for meetings with senior officials from the Obama administration and international financial organizations, said “the critical point is firstly to ensure bilateral cease fire in the 40-kilometre radius zone around the crash site.”

“Secondly, it’s critical to ensure that the civil police component from our partners in France, like Dutch, like Australians is there and the third point is it’s also critical that we are able to ensure the safety and security around site, not just in the 40 kilometre zone,” he said.

However, he stressed that the government’s job was made harder because it had to deal with a constant inflow from Russia of fighters, money and weapons that are aimed at destabilizing Ukraine because of its Western leanings.

“We are punished for our European choice,” he said, adding that the conflict would not be happening at all without Russian support.

“It’s all going on and dragging on because of the influence of outside, because of the inflow of mercenaries, money, heavy weaponry, crossing the border,” Klimkin said. “It’s because mainly the so-called terrorists are actually Russian citizens, a number of them with special links to the Russian security services.”

Russia has denied that it is supplying the rebels with heavy weaponry and has sought to refute Ukrainian and U.S. allegations that its forces have been shelling Ukraine from Russian territory. On Sunday, Secretary of State John Kerry bluntly told Russian Foreign Minister Sergey Lavrov in a phone call that he did not believe Moscow’s denials, according to a State Department readout of the conversation.

Ukraine has been accused of targeting civilians in what it says is a counter-terrorism operation in separatist areas, but Klimkin said the government is making every effort to mitigate collateral damage. And, he blamed the separatists for hiding and placing weaponry in civilian areas.

“They normally place heavy weaponry, like tanks, like rocket-propelled grenades in the centre of living blocks in order to … shell not just our troops but also civilian targets from there,” he said.

Klimkin said he would be seeking additional support from Washington during his visit, including unspecified military equipment, but added that U.S. soldiers on the ground are not needed.